CN103399255A - Method for identifying state of power transformer winding by using pseudorandom sequence - Google Patents

Abstract

The invention provides a method for identifying a state of a power transformer winding by using a pseudorandom sequence. The method comprises the following steps: adopting an M sequence in the pseudorandom sequence as a signal source; after exciting a winding system, collecting input and output signals by using double-channel digital collection equipment; calculating to obtain a pulse response transferring function of the winding system according to the input and output signals; then carrying out correlation function calculation on the input and output signals to obtain a pulse response of the winding system; then describing the state of the winding according to a derivation parameter and a frequency response curve; and judging whether the transformer winding is deformed or not. The testing method disclosed by the invention can be used for comparing amplitude-frequency response curves of the transformer winding and has the consistency. The method disclosed by the invention has the characteristics that the pulse response transferring function of the winding can be directly obtained, the measurement time is short and the like; and furthermore, the method disclosed by the invention can judge the state of the transformer winding according to the change of specific parameters, including poles, null points and the like, of the transferring function, so that the problem in the prior art that technicists easily carry out erroneous judgment is solved.

Description

A kind of method with pseudo-random sequence identification Winding in Power Transformer state

Technical field

The invention belongs to the High-Voltage Technology field, be specifically related to a kind of method with pseudo-random sequence identification Winding in Power Transformer state.

Background technology

Continuous growth along with electrical network, in system, short-circuit current, capacity of short circuit strengthen, happen occasionally in the equipment such as power transformer, reactor of the fortune situation that the fault of type stands that is short-circuited, their winding also will be more prone to run into the faults such as distortion, whether winding state is to deform under winding and normal condition, and it is a basic sign of running state of transformer.Have in existing Transformer Winding detection method, short circuit impedance method, Low Voltage Impulse Method, frequency response method etc., wherein short circuit impedance method is relatively simple to operate, has former to be used for scene, but but range of application is narrow, and sensitivity is not good enough.Low Voltage Impulse Method is quick on the draw, and accuracy is high, but antijamming capability is not enough while using at the scene, and repeatability is bad, and does not also form the equipment of national standard and widespread use.The sensitivity of frequency response method relatively low pressure impulse method decreases, but good stability, repeatable high, the special testing tool of both at home and abroad also according to the frequency response ratio juris, having produced Multiple Type can be chosen for transformer operation and production unit, and present frequency response method is considered to the most reliable winding deformation measuring technology.

Yet frequency response method (FRA method) is existing problems still in use: 1) signal source of FRA test macro when single-frequency is exported, general a plurality of cycles of continuous wave output, and with center section Excitation and response signal, analyzing; Then test analysis on next frequency; This causes the Measuring Time of a FRA method long, is unfavorable for like this fast processing of data.2) analysis and diagnostic techniques need a large amount of historical frequency response pattern.When two amplitudes have bigger difference and the very approximate frequency response curve of curve shape, be easy to produce misjudgement while according to related coefficient, judging, in addition, the data that some engineering technical personnel obtains in the face of frequency response method can rely on the experience of self to improve the reliability of judgement, but rely on professional's micro-judgment shortcoming apparent, this method requires very high for personnel, if without enriching on-site experience, be difficult to judge, and different technician's judgement can there are differences, and determines whether that distortion is difficult to set unified standard.Band segment and full frequency band are analyzed, used related coefficient and mean square deviation as the characteristic quantity that detects deformation of transformer winding.The storage space that takies is large.And, to the graph data of small local difference is arranged, can draw identical feature value and judgement, and, if this small local difference reaction winding situation and trend may cause erroneous judgement and misjudgement, that is to say, more insensitive based on the analytical technology of figure.Therefore, proposing a kind of new detection technique of winding deformation more fast and accurately is necessary.

Summary of the invention

The purpose of this invention is to provide a kind of method with pseudo-random sequence identification Winding in Power Transformer state, it is short that it has Measuring Time, is easy to accurately judge the characteristics of Winding in Power Transformer state.

For achieving the above object, the present invention adopts following technical scheme:

The present invention includes following steps:

1) the M sequence in the employing pseudo-random sequence is as signal source, after the winding system excitation, with two-channel digital collecting device Gather and input, output signal;

2) calculate the impulse response transport function of winding system according to input, output signal;

3) describe winding state according to the impulse response transport function of winding system and the derivative parameter of impulse response transport function, and then judge whether Transformer Winding deforms.

In described step 1) the clock frequency of M sequence be 500kHz to 6MHz, progression is that 7 rank are to 13 rank.

Described step 2) in, the impulse response transport function obtains by following process computation: according to Wei Na-Hough integral equation, the cross correlation function of autocorrelation function, input and output function by input signal calculates, obtain the instantaneous information sequence of impulse response sampling, and then obtain the impulse response transport function.

Described step 2) in, impulse response transport function G (s) is expressed as:

$G\left(s\right)=\frac{c_1}{s-s_1}+\frac{c_2}{s-{\mathrm{<figure-callout\; id="2"\; label="s"\; filenames="HDA00003472906800013.png,HDA00003472906800031.png"\; state="\{\{state\}\}">s</figure-callout>}}_2}+...+\frac{c_n}{s-s_n}=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}\frac{c_i}{s-s_1}---\left(4\right)$

In formula, s ₁, s ₂... s _nAnd c ₁, c ₂..., c _nFor 2n a to be asked unknown number.

In described step 3), derivative parameter is zero limit and impulse response transfer-function coefficient.

with respect to prior art, the beneficial effect that the present invention has: the present invention is owing to adopting M sequence in pseudo-random sequence as signal source, detect power transformer, the state of the winding kind equipments such as reactor, can directly obtain the system impulse response transport function, and utilize it and it derivative parameter and figure to describe winding state, can judge whether to deform, simultaneously can obtain the frequency response curve auxiliary judgment of impulse response transport function according to the zero limit that the impulse response transport function comprises, can be more comprehensively the real information of reflected measurement object reliably, has Measuring Time short, be easy to accurately judge the characteristics of Winding in Power Transformer state.

Description of drawings

Fig. 1 is M sequence generating device block diagram of the present invention;

Fig. 2 is the M sequence waveform that the present invention tests injection;

Fig. 3 is Gather and input of the present invention, output signal; Fig. 3 (a) is input signal, and Fig. 3 (b) is output signal;

Fig. 4 is the mode of connection of winding signal injection-detection;

Fig. 5 is simplex winding M sequence Injection Signal test wiring diagram;

Fig. 6 is the double winding M sequence Injection Signal test wiring diagram on the iron core single-column;

Fig. 7 is that the present invention tests the amplitude-frequency response that winding obtains.

Embodiment

Below in conjunction with accompanying drawing, the present invention is described in further detail.

, referring to Fig. 1, the present invention includes following steps:

1) winding of transformer is regarded a class object to be identified as, by using the method in system identification theory, the M sequence in the employing pseudo-random sequence is as signal source (as shown in Figure 2), wherein, the clock frequency of M sequence be 500kHz to 6MHz, progression is that 7 rank are to 13 rank; After the winding system excitation, with two-channel digital collecting device Gather and input, output signal;

2) calculate the impulse response transport function of system according to input, output signal.

Detailed process is as follows:

At the input end of winding system, the M sequence signal x (k) (as shown in Fig. 3 (a)) that input is produced by pseudo-random sequence generating device, utilize the two-channel digital collecting device to gather output signal y (k) (as shown in Figure 3 (b)) at output terminal; According to Wei Na-Hough integral equation, the information sequence g (nT) that impulse response sampling is instantaneous, the cross correlation function of autocorrelation function, input and output function by input signal calculates.

, if producing the clock pulse interval of M sequence is Δ, can obtain discrete Wei Na-Hough equation:

$R_{\mathrm{xy}}\left(\mathrm{\&tau;}\right)\underset{k=0}{\overset{N-1}{\mathrm{\&Sigma;}}}\mathrm{\&Delta;g}\left(\mathrm{k\&Delta;}\right)R_x(\mathrm{\&mu;\&Delta;}-\mathrm{k\&Delta;})---(2-7)$

At this moment, have:

$\left\{\begin{array}{c}{R}_{\mathrm{xy}}=\mathrm{Rg\&Delta;}\\ g=\frac{1}{\mathrm{\&Delta;}}{R}^{-1}{R}_{\mathrm{xy}}\end{array}\right.---(2-8)$

In formula:

R _xyT is input and the cross correlation function of exporting

$R=\left[\begin{array}{cccccc}{R}_x\left(0\right)& R_x(-1)& .& .& .& R_x(-N+1)\\ R_1\left(1\right)& R_x\left(0\right)& .& .& .& R_x(-N+2)\\ .& .& & & & .\\ .& .& & & & .\\ .& .& & & & .\\ R_x(N-1)& R_x(N-2)& .& .& .& R_x\left(0\right)\end{array}\right]$

$g=\left[\begin{array}{c}g\left(0\right)\\ g\left(1\right)\\ .\\ .\\ .\\ g(N-1)\end{array}\right],$ $R_{\mathrm{xy}}=\left[\begin{array}{c}{R}_{\mathrm{xy}}\left(0\right)\\ R_{\mathrm{xy}}\left(1\right)\\ .\\ .\\ .\\ R_{\mathrm{xy}}(N-1)\end{array}\right],$

, because the M sequence is two formula sequences, calculate R ^-1Be easy to, its autocorrelation function is:

$R_x\left(k\right)=\left\{\begin{array}{c}{a}^2,k=0\\ -\frac{a^2}{N},1\&le;k\&le;N-1\end{array}\right.---(2-9)$

Can obtain impulse response function g:

$g=\frac{1}{a^{2}r(N+1)\mathrm{\&Delta;}}\left[\begin{array}{cccccc}2& 1& .& .& .& 1\\ 1& 2& .& .& .& 1\\ .& & & & & .\\ .& & & & & .\\ .& & & & & .\\ 1& 1& .& .& .& 2\end{array}\right]\mathrm{XY}---(2-10)$

In formula:

$Y=\left[\begin{array}{c}y\left(0\right)\\ y\left(1\right)\\ .\\ .\\ .\\ y(\mathrm{rN}-1)\end{array}\right]$

$R_{\mathrm{xy}}=\left[\begin{array}{c}{R}_{\mathrm{xy}}\left(0\right)\\ R_{\mathrm{xy}}\left(1\right)\\ .\\ .\\ .\\ R_{\mathrm{xy}}(N-1)\end{array}\right]$

$X=\left[\begin{array}{cccccc}x\left(0\right)& x\left(1\right)& .& .& .& x(\mathrm{rN}-1)\\ x(-1)& x\left(0\right)& .& .& .& x(\mathrm{rN}-2)\\ .& .& & & & .\\ .& .& & & & .\\ .& .& & & & .\\ x(-N+1)& x(-N+2)& & & & x(\mathrm{rN}-N)\end{array}\right]$

The Transformer Winding system can be expressed as with difference equation:

g(t ₀)+a ₁g(t ₀+Δ)+"+a _ng(t ₀+nΔ)=0 （3）

Time is postponed Δ successively, can write out n equation, simultaneous solution they, can obtain n coefficient of difference equation, obtain the difference equation of Transformer Winding system.

To a Linear Time-Invariant System, if the root of the secular equation of impulse response transport function G (s) is s ₁, s ₂..., s _n, its impulse response transport function G (s) can be expressed as:

$G\left(s\right)=\frac{c_1}{s-s_1}+\frac{c_2}{s-{\mathrm{<figure-callout\; id="2"\; label="s"\; filenames="HDA00003472906800013.png,HDA00003472906800031.png"\; state="\{\{state\}\}">s</figure-callout>}}_2}+...+\frac{c_n}{s-s_n}=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}\frac{c_i}{s-s_1}---\left(4\right)$

In formula, s ₁, s ₂..., s _nAnd c ₁, c ₂..., c _nFor 2n a to be asked unknown number.

G (s) is carried out inverse Laplace transform, can obtain the impulse response function g (t) of system:

$g\left(t\right)=c_1{e^{s_1}}^t+c_2{e^{s_2}}^t+...+c_n{e^{s_n}}^t---\left(5\right)$

Simultaneous t+ Δ, the t+2 Δ ..., t+n Δ impulse response function and formula (3) constantly, through calculating the impulse response transport function G (s) that can obtain system.

3) thereby, pick out the mathematical model of system, and utilize impulse response transport function G (s) and its derivative parameter and figure to describe winding state, and then judge whether winding deforms; Wherein, derivative parameter is zero limit and impulse response transfer-function coefficient.

Shown in Figure 4, in winding system, be easy to detect winding deformation owing to getting the mode of connection of neutral point current as response signal, the present invention adopts the mode of connection as shown in Figure 4, injecting the test source signal to power transformer high-pressure side winding is the M sequence signal, low-pressure side winding collection signal.

For the Measurement accuracy winding deformation, Test input signal there is strict demand, therefore the principle that the present invention deposits based on feedback shift simultaneously and XOR calculates has proposed a kind of pseudo-random sequence generating device, this device comprises provides M sequence, isolation drive, Voltage-output part, produce the M sequence by the pseudo-random sequence source during work, the M sequence that produces through the electrical isolation of high speed optoelectronic coupling, MOS to tube drive circuit and MOS to the tube voltage output, M sequence signal source is provided.

Shown in Figure 1, winding M sequence Injection Signal test wiring: by the pseudo-random sequence source, produce the M sequence, the M sequence that produces through the electrical isolation of high speed optoelectronic coupling, MOS to tube drive circuit and MOS to the tube voltage output, inject winding to be measured, then utilize the two-channel digital collecting device, Gather and input, output signal, then calculate, differentiate simultaneously.

Referring to Fig. 5 and shown in Figure 6, in the present invention, experimental wiring both can adopt simplex winding M sequence Injection Signal test wiring, also can adopt the double winding M sequence Injection Signal test wiring on the iron core single-column.

Referring to Fig. 7, the present invention can obtain the frequency response curve of impulse response transport function according to the zero limit that the impulse response transport function comprises, utilize this frequency response curve can carry out auxiliary judgment, can be more comprehensively the real information of reflected measurement object reliably.

Claims (5)

1. the method with pseudo-random sequence identification Winding in Power Transformer state, is characterized in that, comprises the following steps:

1) the M sequence in the employing pseudo-random sequence is as signal source, after the winding system excitation, with two-channel digital collecting device Gather and input, output signal;

2) calculate the impulse response transport function of winding system according to input, output signal;

3) describe winding state according to the impulse response transport function of winding system and the derivative parameter of impulse response transport function, and then judge whether Transformer Winding deforms.

2. a kind of method with pseudo-random sequence identification Winding in Power Transformer state according to claim 1, is characterized in that, in described step 1) the clock frequency of M sequence be 500kHz to 6MHz, progression is that 7 rank are to 13 rank.

3. a kind of method with pseudo-random sequence identification Winding in Power Transformer state according to claim 1, it is characterized in that, described step 2) in, the impulse response transport function obtains by following process computation: according to Wei Na-Hough integral equation, the cross correlation function of autocorrelation function, input and output function by input signal calculates, obtain the instantaneous information sequence of impulse response sampling, and then obtain the impulse response transport function.

4. a kind of method with pseudo-random sequence identification Winding in Power Transformer state according to claim 1, is characterized in that described step 2) in impulse response transport function G (s) be expressed as:

$G\left(s\right)=\frac{c_1}{s-s_1}+\frac{c_2}{s-s_2}+...+\frac{c_n}{s-s_n}=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}\frac{c_i}{s-s_1}---\left(4\right)$

In formula, s ₁, s ₂..., s _nAnd c ₁, c ₂..., c _nFor 2n a to be asked unknown number.

5. a kind of method with pseudo-random sequence identification Winding in Power Transformer state according to claim 1, is characterized in that, in described step 3), derivative parameter is zero limit and impulse response transfer-function coefficient.

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